Axially chiral 3,3 '-bi(1-benzothiophene)-2,2 '-dicarboxylic acid and its derivatives

作者：Mezlova M; Petrickova H; Malon P; Kozmik V; Svoboda J^*

来源：Collection of Czechoslovak Chemical Communications, 2003, 68(5): 1020-1038.

DOI：10.1135/cccc20031020

• Ullmann reaction
• homocouplings
• benzothiophenes
• bi(1-benzothiophene)
• resolution
• stereoselective reduction
• biaryls
• axial chirality
• CD spectroscopy

Ullmann dimerization of substituted methyl 3-X-1-benzothiophene-2-carboxylates 1-7 (X = Cl, Br) gave rise to the corresponding dimeric 3,3'-bi(1-benzothiophene) esters 8-13. Resolution of the title acid 20 by fractional crystallization of its mono- and bisquininium salt afforded pure (R)- and (S)-enantiomers, the optical purity and absolute configuration of which was confirmed by CD spectrometry and by X-ray crystallography. Ullmann dimerization of chiral oxazolines 23 and 24 derived from 2 proceeded without any diastereodifferentiation. Reduction of (R)- and (S)- 20 afforded the corresponding (R)- and (S)-diols 29, which served as chiral ligands in a model enantioselective reduction of acetophenone. (R)- and (S) 1-phenylethan- 1-ol were formed in 28 and 29% e.e., respectively.

• 出版日期2003